Comparison of different approaches for the simulation of boilers using oil, gas, pellets or wood chips

A detailed model for the simulation of boilers using oil, gas, pellets or wood chips has been developed and compared with measurements. Approaches of different complexity for the simulation of steady state flue gas losses were tested. The more physical approaches are able to reproduce measured data better than the simpler empirical models, but they also require more model parameters to be determined and a higher simulation effort. Cycling behaviour of the simple one-node thermal mass approach of the model was compared with measured cycling behaviour of a pellet boiler. With the proper values for the relevant boiler parameters, cycling behaviour is reproduced well. With the implementation in a FORTRAN-dll that can be called from TRNSYS, a tool is now available that suits the needs of scientists as well as planners and product developers that use energy systems simulation tools.